Like others, I was expecting a Geekbench score in the 30,000s (if not the 40,000s). What's going on here?

This Geekbench result is from a pre-release machine with a radical new design. There could be any number of hardware, firmware, and software issues that affect performance. In particular, overheating problems thanks to the new thermal core could cause the processor to throttle performance, lowering the overall Geekbench score.

The processor in the new Mac Pro is running over 300 MHz slower than the processor in the current Mac Pro. Generally, processor frequency decreases as processor core count increases. In order to put 12 cores in a single processor machine, Apple has to use slower processors. If Apple could use 6- or 8-core processors instead of 12-core processors, the processors could reach speeds of 3.5 GHz instead of 2.7 GHz.

That said, Apple's claim of "up to 2x faster" floating point performance may be optimistic. The new "Ivy Bridge" Xeon processor in the new Mac Pro has instructions that can process twice the amount of data as the "Westmere" Xeon processors in the current Mac Pro. The problem is that only certain kinds of software can take advantage of these instructions.

It's too early to say that the new Mac Pro is a disappointment. Even if performance doesn't improve, Apple's managed to get better performance out of a system that's an eighth the size of the current system.

John Poole is the founder of Primate Labs and lives in Toronto, Ontario with his wife Deborah. You can find John on Twitter or Google+.